The invention relates to a method and an apparatus for time-optimized positioning of at least one body in a desired target position, by which the body is brought into the target position independently of the traversed path and without overshoot.
In known apparatus for the mechanical positioning of mechanical elements of peripheral equipment, such as for example tape memories, disc memories, reading heads, and printing heads, or for numerically controlled movements of machine tools of drafting machines or similar apparatus, it is desired that the target position is reached in a time-optimized manner without overshoot or oscillation about the target location and without regard to the already traversed positioning path.
A known method, or rather arrangement, of the data processing technology is described in U.S. Pat. No. 3,893,695, Rickert. This known method does not choose the optimum deceleration characteristic, but rather one which crosses the optimum deceleration characteristic. The actual process of deceleration, or rather of the positioning of the body, occurs through step-like approximations of the deceleration curve. The disadvantage lies in that the positioning process does not occur in the optimum time.
Another known arrangement is disclosed in the published German patent application DE-OS 2,334,455 (Siemens AG). In this known arrangement, the body is brought to rest through a number of braking cycles. An approximating process calculates the number of the braking cycles and their respective deceleration magnitudes. Here the approximation process is a certain approximation of the ideal deceleration characteristic. An essential disadvantage of this known arrangement lies in that the condition of time optimization is not fulfilled because of the numerous braking processes, or rather braking cycles. This is partly the case because the last part of the travel, just before the desired position, is in a creep mode.
An object of the present invention is to avoid the disadvantages of the known methods or apparatus. The present invention permits positioning the body in accordance with the theoretical braking characteristic, and not in accordance with some approximation of this braking characteristic, as is the case for known systems. Furthermore, the present invention makes feasible for the positioning to be in accordance with the definition of "time-optimized processes", that is, the magnitude of the limiting parameter is held at maximum and its sign may only change once during the entire process. This definition is described in the book, "Rechengeraete in automatischen Systemen", by Prof. Dr. A. A. Feldbaum (Moskau), Verlag R. Oldenbourg (publisher), Muenchen, 1962, page 193. With regard to the present invention, the limiting parameter is the maximum torque of the motor which brings the body to be positioned into its target position. In accordance with the invention, the sign of this torque is changed only once during the positioning process.
It is a further purpose of the invention to permit the body to be moved with various chosen and controlled speeds. The body to be positioned may be, for example, a reading head, a recording head in memories or in peripheral equipment of data processing technology, or a slide of an instrument for plotting or drafting.